MassTech (United States)

In this paper, we describe the development of a prototype differential absorption fluorescence lidar for nighttime tropospheric formaldehyde (H 2 CO) concentration profiling. H 2 CO has a strong absorption band in the 352-357nm region and fluoresces strongly in the 390-500nm region. Here, we obtain high sensitivity (∼0.1ppb) measurements of H 2 CO profiles from differential fluorescence signals obtained by injection seeding a Nd:YVO laser and tuning its wavelength on and off the peak of a strong absorption line. The fluorescence signal strength is further improved by using a multi-line bandpass filter whose pass-bands are aligned to multiple fluorescence peaks of H 2 CO. A H 2 CO filled photo-acoustic absorption cell is utilized for tuning the seed laser wavelength to the center of absorption line.

A field-deployable quadrupole ion-trap mass spectrometer with an atmospheric pressure interface is designed, built, and characterized. The instrument enclosure (48 cm × 43 cm × 42 cm) includes a roughing pump and a helium lecture bottle; the total weight of the instrument is 68 kg. Peak power consumption during the instrument operation is ∼500 W. The instrument has a mass range of m/z 30-2500, across which it provides better than unit mass resolution. The typical peak width at half height is 0.3 Th for a scan speed of 4000 Th/s. Operation of the instrument with electrospray and atmospheric-pressure matrix-assisted laser desorption ionization (AP-MALDI) ion sources is demonstrated. AP-MALDI analysis of low femtomole amounts of peptides reveals that the sensitivity of the instrument is on par with modern commercially available quadrupole ion-trap mass spectrometers. Tandem mass spectrometry capabilities of the instrument include simultaneous isolation and fragmentation of several different compounds. Two ways to reduce the size, weight, and power consumption of the portable instrument were explored, and results of these initial studies are presented. One of the ways includes utilization of hydrogen as a buffer gas for operation of the ion-trap mass analyzer in combination with a metal hydride method for storage of hydrogen in a compact rechargeable cartridge. Furthermore, careful selection of the inlet capillary dimensions allowed to eliminate the first "1 Torr" stage of the differential pumping without any significant loss of the instrument sensitivity. The elimination of this first pumping stage removed two turbo drag pumps, which substantially decreased the instrument's maximum power consumption (to ∼300 W in peak use, and ∼150 W during standby), as well as its size (to 30 cm × 43 cm × 50 cm) and weight (to 35 kg).

The mechanism of atmospheric pressure (AP) laser ionization of water and water/glycerol liquid samples at a 3-microm wavelength is studied experimentally. For the ion desorption, an in-house built Yb : YAG-pumped optical parametric oscillator (OPO) infrared (IR) laser has been coupled with AP MALDI ion source interfaced to an ion trap mass spectrometer (MS). It has been shown that water is primarily responsible for ion generation in water/glycerol samples, while glycerol increases the solution viscosity and decreases the water evaporation rate and sample losses. In contrast to AP UV-MALDI, the electric field in the case of AP IR-MALDI does not assist in ion production. It was found that the absence of the electrical field provides the optimum ionization condition both for water and water/glycerol liquid samples at the 3-microm laser irradiation. A two-stage ion formation mechanism, which includes the initial emission of microdroplets and release of molecular ions at the second stage, can explain the experimentally observed ion signal dependencies upon the voltage applied between MS inlet and the MALDI sample plate. Postionization using additional corona discharge APCI increases the observed signal by approximately 50%, which indicates that some portion of the analyte is desorbed in the form of neutral molecules.

Abstract This paper describes how combining certain aspects of systems re‐engineering with intelligence analysis creates a hybrid methodology resulting in a major transformation of the intelligence analysis discipline. The world and technology have changed over the years and now actionable intelligence must be provided in a collaborative environment prior to and during crises. Analysis of today's intelligence complexities demands a move away from analytic thinking to systems thinking. By introducing the concept of a “system” into the process of intelligence analysis, analysts are empowered to create and use systems models. These system models comprise all of the systems necessary for world‐class intelligence analysis – to include systems‐of‐systems of target, customer, and analyst. To the degree that these models are sufficiently accurate, the analyst can apply logic and judgment to produce projections of the future. Therefore, a continuing close customer‐analyst collaborative relationship enables professional determination of the most likely consequences of alternative customer operations.

A recently developed commercial atmospheric pressure matrix-assisted laser desorption/ionization (AP-MALDI) source (MassTech, Inc.) was modified to adopt commercially available DIOS plates (Mass Consortium Corp.) for the studies of laser desorption from the surface of porous silicon under atmospheric pressure conditions. The feasibility of atmospheric pressure laser desorption/ionization from the surface of porous silicon (AP-DIOS) was demonstrated. The advantages of this new AP-DIOS technique include reasonably good sensitivity (subpicomole range for standard peptide mixtures), simplicity of sample preparation, uniformity of target spots and the absence of matrix peaks in the spectra. The AP-DIOS source was interfaced with a commercial ion trap (LCQ Classic, Thermo Finnigan) which additionally provides a unique MS(n) capability. The AP-DIOS spectrum of 250 fmol of unseparated tryptic digest of bovine serum albumin (BSA) was compared with that of AP-MALDI for the same compound. AP-DIOS offers significantly better coverage for the digest components in the mass range 200-1000 Da. The combined data of both techniques enabled us to nearly double the number of matched peaks in BSA digest analysis compared with AP-DIOS or AP-MALDI analysis separately.

Performance characteristics of an infrared (IR) matrix-assisted laser desorption/ionization (MALDI) quadrupole ion trap (QIT) mass spectrometer are presented. Both an IR laser and an ultraviolet (UV) laser have been coupled to the MALDI ion source, allowing for a comparative study of the spectra obtained for the same analyte molecules taken at these two wavelengths. The mass range of the QIT instrument was extended by operating it at a frequency as low as 200 kHz. The results presented for small and medium-size peptides demonstrated a lesser degree of analyte ion fragmentation in the case of the IR-MALDI source compared with that obtained using the UV-MALDI source. Due to the fragmentation phenomenon, the mass resolution for cytochrome C ions(MW12384 Da) was an order of a magnitude higher in the case of IR-MALDI compared with the use of UV-MALDI. This phenomenon has been shown to effect the calibration of the trap instrument for higher masses.